2.6.2 Distribution

Distribution is characterised by plasma protein binding (expressed as the unbound fraction, fu), distribution coefficient (logD), and polar surface area — a...

Distribution is characterised by plasma protein binding (expressed as the unbound fraction, fu), distribution coefficient (logD), and polar surface area — a PSA below approximately 90 Ų is generally required for central nervous system penetration. Volume of distribution (Vd) values of 0.1–1 L/kg suggest predominantly plasma confinement, while values exceeding 5 L/kg indicate extensive tissue distribution.